Sleeping247 has finally posted all the information we require. Here's a copy of his post, all due credit goes to him, he's a lifesaver!
FOR NTSC-J USERS:
I have a NTSC-J 3.0J Nintendo Wii updated online with the latest version.
I tried the two disk method earlier, and it WORKS FOR NTSC-J OWNERS
There is just ONE thing you must change.
1. Download the game
2. Extract the downloaded files with WinRar into an ISO
3. Make TWO NEW FOLDERS.
4. Copy the original ISO and paste one ISO into EACH of the new folders you have created.
5. Run ONE of the copyed ISOs (leave the original alone...!) with Brick Blocker.
6. Run the OTHER copyed ISO in Region Frii (convert FROM USA to JAP)
7. Now burn TWO discs. ONE with the ISO that was "BrickBlocked" and the second disc with the one that was "Region Friid"
8. Now you have two copies of Metroid Prime 3, right?
9. Try to insert the BRICK BLOCKED game. Black screen. No problem.
10. Insert the Region Friid game. It will now say "Initiating Wii System Update" and you can press "OK". Press OK, then on the next message press "I accept".
11. NOW! Let the update run for SOME SECONDS. Let perhaps 10-15% of the bar get blue, then UNPLUG your wii console!!!!!!
12. Insert the power again, turn on your Wii. You do NOT have double channels now.
13. Insert the game that you Brick Blocked (the one that used to give you a black screen...). Let it load, and BOOM; it works. Now you have a working Metroid Prime game and a non-doubled Wii
I let mine update for Twelve (12) seconds before turning it off.
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An update from Cocytean's summary earlier
All users:
The game updates your Wii to allow it to be played, but does NOT contain a firmware update on it - your firmware version will remain the same.
If you Brickblock the file, the game WILL NOT PLAY - the update is necessary for it to be run.
The game has been confirmed to work on Pal Wiis several times, including those with Wiikeys, but at the cost of duplicating the weather and news channel.
To Work around the duplicate channels,
PAL Users follow the above instructions, BUT
6. Run the OTHER copyed ISO in Region Frii (convert FROM USA to PAL)
NTSC-J Users follow the above instructions, BUT
6. Run the OTHER copyed ISO in Region Frii (convert FROM USA to JAP)
Additional Information:
the Brick Blocker designer is on holiday, so there's no chance of him doing a work around this update any time soon.
What do the duplicate channels do?
They are non-functional. Your original channels will work as normal though.
These duplicated channels cannot be removed, and cannot be accessed. However, you can move the channels to a different location on your Wii channels should the aesthetics of duplication displease you.
No-one knows for sure yet whether or not this is an attempt by Nintendo to 'flag' modded Wiis - more likely is some differing region pieces of code are arguing with one another. All other channels, Internet connection and the like work as normal.
What does interupting the update do?
We arent sure yet, and no-one knows for sure until, and if Nintendo take action. In the past, many users have turned off their power when updating (whether intentional or unintentional) and they have been able to update at a later stage without any problems.
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I must say though, it was disappointing at the lack of assistance NTSC-J users got earlier. Constant requests by multiple NTSC-J Owners kept getting ignored. Heres one for the team.
It also annoys me at how many users keep asking the same questions over and over. Fair enough, you dont want to read through 20 pages, but at least read through three to five pages and you will have at least SOME idea.